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Command Loss Timer Reset
Command Loss Timer Resets are part of the CCSDS communications system to spacecraft either in Earth orbit or beyond Earth orbit. The Command Loss Timer Reset, if it is not received in a timely manner by the spacecraft, generally forces the spacecraft to engage in safety and self-protection procedures. * Command Loss Timer Reset systems involve both hardware and software, whereas watchdog timers are essentially hardware-only affairs. * Most spacecraft have more than one Command Loss Timer Reset for subsystem level safety reasons, with the Voyager craft using at least 7 of these timers. * Technically the Command Loss Timer Reset is a glorified array of Watchdog timers, each with different settings. Overall spacecraft safety is very important for missions of multi-year duration. This means that the Command Loss Timer Reset subsystem has to be used to avoid multiple computer reboot events. Generally speaking, when a computer reboots it decreases the overall safety of the spacecraft for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCSDS
The Consultative Committee for Space Data Systems (CCSDS) was founded in 1982 for governmental and quasi-governmental space agencies to discuss and develop standards for space data and information systems. Currently composed of "eleven member agencies, twenty-eight observer agencies, and over 140 industrial associates," the CCSDS works to support collaboration and interoperability between member agencies through the establishment of data and system standards. According to the organisation's website, more than 1000 space missions have utilized data and systems standards created by CCSDS. The activities of the CCSDS are organized around six topic areas and composed of many working groups within the overall Collaborative Working Group Environment (CWE). Publications and standards The CCSDS is divided into 6 Technical areas: * Space Internetworking Services * Mission Operations And Information Management Services * Spacecraft Onboard Interface Services * System Engineering * Cross Sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watchdog Timer
A watchdog timer (sometimes called a ''computer operating properly'' or ''COP'' timer, or simply a ''watchdog'') is an electronic or software timer that is used to detect and recover from computer malfunctions. Watchdog timers are widely used in computers to facilitate automatic correction of temporary hardware faults, and to prevent errant or malevolent software from disrupting system operation. During normal operation, the computer regularly restarts the watchdog timer to prevent it from elapsing, or "timing out". If, due to a hardware fault or program error, the computer fails to restart the watchdog, the timer will elapse and generate a timeout signal. The timeout signal is used to initiate corrective actions. The corrective actions typically include placing the computer and associated hardware in a safe state and invoking a computer reboot. Microcontrollers often include an integrated, on-chip watchdog. In other computers the watchdog may reside in a nearby chip that connec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dead Man's Switch
A dead man's switch (see alternative names) is a switch that is designed to be activated or deactivated if the human operator becomes incapacitated, such as through death, loss of consciousness, or being bodily removed from control. Originally applied to switches on a vehicle or machine, it has since come to be used to describe other intangible uses, as in computer software. These switches are usually used as a form of fail-safe where they stop a machine with no operator from a potentially dangerous action or incapacitate a device as a result of accident, malfunction, or misuse. They are common in such applications in locomotives, aircraft refuelling, freight elevators, lawn mowers, tractors, personal watercraft, outboard motors, chainsaws, snowblowers, tread machines, snowmobiles, amusement rides, and many medical imaging devices. On some machines, these switches merely bring the machines back to a safe state, such as reducing the throttle to idle or applying brakes while leav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safe Mode (spacecraft)
Safe mode is an operating mode of a modern unmanned spacecraft during which all non-essential systems are shut down and only essential functions such as thermal management, radio reception and attitude control are active. Safe mode is entered automatically upon the detection of a predefined operating condition or event that may indicate loss of control or damage to the spacecraft. Usually the trigger event is a system failure or detection of operating conditions considered dangerously out of the normal range. Cosmic rays penetrating spacecraft electrical systems can create false signals or commands and thus cause a trigger event. The central processor electronics are especially prone to such events. Another trigger is the lack of a received command within a given time window. Lack of received commands can be caused by hardware failures or mis-programming of the spacecraft, as in the case of the Viking 1 lander. The process of entering safe mode, sometimes referred to as ''safing'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
